Road making and material used therein



Patented Jan; 6, v

umwmm EDWIN'C. WALLACE, or NEWTON, MASSACHUSETTS Roan MAKING AND MATERIAL USED 'rnnnnm No Drawing.

The present invention relates to the manufacture of roads (under which termI intend to embrace not only ordinary roadways for openvehicular trafliqbutalso walks, paths, roofs, etc.) and also embraces a novel com 7 position of matter the use of which constitutes results.

impregnating bitumen is of much harder consistency than in the rocks mentioned.

above: Many attempts have been made to use the kinds of rock impregnated with'hard bitumen, in road making with results which are extremely variable and wholly uncertain. Fairly good results have been obtained in some cases when efforts were made to soften the bitumen with which the rock was impregnated by the addition of a suitable flux or softening agent. By this means compositions were sometimes produced which gave excellent results, but quite differentand'unsatisfactory results were so frequently obtained that attempts have been difficulty, v

In some of these attempts themethodsoutlined have been sovery elaborate as to be suitable only for the laboratory or small scale production.

In the process herein described anJattempthas beenlmade to soften the bitumen con- 7 tained in the rock by the addition, in a specific manner described below, of. suitable fluxing. orsoftening agent of the same general char-' acter which has been proposed, but the meth- 1 'odhas been so modified that uniformly good vary'with its yiscosity'but generallyi comes results may be obtained without the necessity of carrying the refinements beyond the limitsof practicability fromthe standpoint of cost. In this process it is not necessary to heat the asphalt rock and except in cases where made to overcome the Application filefa'm a, 1e2aeser a1 No, 290,052.

heavy gravity, viscous fluxes are used it is not necessary to heat the flux. 'lVhere, however, a heavy gravity and viscous fluxis used, itis advisable to heat. it to somewhatabove the boiling point of Water before it is added to the rock asphalt.

In briefithe process 'may be follows: a The asphalt rock is broken into fragments as I which will pass a screen, the openings 'off which will give particlesofjthe maximum size desired. The reduced material is then separated by screens into two portions, one much finer than "the other. 5 r

These sizes may vary according to the purpose for which the composition is to be used,

but as examples of material suitable inmost s cases, the following may be given:

The rock may-be crushed'into sizes substantiallyall of which-willpass a screen having;

inch or inch openings'and the fine material which passes an 8-10 mesh screen, is then kept separated from the portion retained thereon. This formstwo fractions, acoarse fraction anda fine fraction;

The approximate proportionpf coarse to finemateria-l obtained by crushing and screen- 7 'ing, is noted in order thatthese materials may be recombined later iii substantially the same ratiog f f T -After the crushed rock has been separated as described, the coarse material is introduced into any suitable mixing device andto it' the necessary proportion of fluxing orsofteni agent isadded and: these'iingredients then thoroughly mixed. The' finerfmateri-alj obtained by screening as above is thereafter added and the mingled;

v entire mass thoroughly com- The proportions ofcoarse and finecrushed rock maybe' varied at will, but by using itin substantially the same proportions into ich ,therock' breaks down, there is no excess either'coarse or: fine and no loss of material.- The amount of flux or softening agentwill within thelim'itsof 1 1204 75 byjweightof the rock which wouldbe approximately equal w. 3" to 10 gallonsof flux toeach ton otcrushed V Any suitable flux for asphalt be used, but I prefer one derived from Mexican or Californiapetroleum and also by preference use one having a viscosity of less than 2000 seconds on Engler viscosimeter at 25 C., with specific gravity coming within a range of .82 to .96 at 25 o. v

lVithIthis relatively small proportionof softening agent, itis essential that proper distribution he obtained.

B 1 separating the crushed rock into coarse and fine fractions and applying the fiuxing material to the coarse material only, the component pieces in this fraction become thoroughly coated with the flux and act-as a dispersing medium; t0 distribute said fluxing materialto and thr ough the finer fraction,

(:luringthe subsequent mixing and compres- S1QIl Op8I2Lt-1 O11S. The flux-treated coarse .ma terlal is mixed with the finesin-theiraorlginal rat-i0.

i- EachoffthefiuX-coated coarse piecesbe- 7 comes 1n effect a. nucleus around which the I fiIlBP-PEII'tIClQS'iLCCIGtG and becomecoated by contact and difiusion.

withhard bitumen, the successive stepsof crushing the rock asphalt to a desired size,

separating it into two portions of respectively coarse and fine particles, mixing the coarse portion with a small amount of asphalt fiux ing or softeningagent, then recombining the coarse andfine material in substantially the proportions in which the rock breaks down. '2. A process Which comprises crushing a r ock containing hard asphalt, until all of the rock willipass;a screen of inchmesh, then screening out the fine material from the -coarser'mater-ial contained therein, well mixing the coarser portion with about 1 to 4% "of fiuxing' "oil, "thereafter adding thefiner material, in about the proportions intoiwhich the coarse and fine portions wereoriginally separated, 7 v p In testimony-whereof I afiix my signature.

' EDWI o. WALLACE.

TEhis-miXture-isthen spreadon the-"foun 1 i dation, preferably at atmospheric tempera fjture,-t-o thedesired thickness and rolled or otherwise compressed and compacted toform a road, walk or'other desired article.

1 1 If it were attempted to mix the whole of I the coarse and: fine (without separation) directly with this small amountof flux, or if it were attempted-to-mix the fine material with this small-amountof flux and subsequently incorporate the coarser-material, the flux or I softening jagent would come into"contact l "with thefiner materialflbefore the coarse .particles;wouldbe'properly coated and the fine material would act as a sponge'or abrender it practically impossible tov distribute the small amountof flux required, uniformly through the mass.- Thefinal result would be an improperly balanced composition 'much v orbent, andt-akeup much more of theflux 7 ing agent than is actually'needed by it, and

richerand' softer in some portions thanin others. If the softer portions richer in. the fiuxing material are well adapted for the purf culty isioyerc'ome, the finermaterial does-not carry more than its proportionate share f of the fluxing agent, the compositionis pn'operly' e ll ed, easily controlled and excellent and i v uniform results. can be Obtainedifff q .1. Int-he preparation of bituminous av;

ing mixtures from rock asphalt impregnated j 

